Magnetization Dynamics Triggered by Femtosecond Laser Excitation

Femtosecond (fs) laser pulses are among the shortest stimuli in contemporary experimental physics. Controlling the magnetic state of media with ultrashort laser pulses is a rapidly growing research area which promises to revolutionize information processing by achieving the fastest possible and least dissipative magnetic recording [1,2]. The interaction of light with electrons, within the electric-dipole mechanism, conserves the electron spin. As a result, the mechanisms allowing femtosecond optical control of magnetism are among the most heavily debated fundamental questions in contemporary condensed matter research.

In my lecture I will review recent progress in the field of femtosecond opto-magnetism. Several examples revealing the ways to boost the susceptibility of magnetic metals and dielectrics to ultrafast optical excitation will be discussed. For instance, the importance of interfaces [3] and domain walls [4] will be emphasized in the case of femtosecond opto-magnetism of Co/Pt multilayers. We will highlight the role of rare-earth ions in the case of effective optical control of magnetism in orthoferrites [5] and the role of doping in the case of photo-magnetic recording in iron garnets [6]. It will be also shown that non-collinear spin structures are more susceptible to femtosecond laser excitation that their collinear counterparts [7].